This invention relates to electrical switch arrangements and more particularly to coaxial cable switches employing sealed reed contacts.
Switch arrangements in which electrical continuity in a coaxial transmission cable is controlled by a pair of reed contacts in series with the center conductor of the cable are well known in the art as is the problem of providing sufficient isolation when the contacts are open. One prior art switch construction directed to the latter problem is described in U.S. Pat. No. 3,355,684, issued Nov. 28, 1967, to D. S. Church et al., and provides for the serial connection of at least three spaced reed contact pairs in the center conductor of a coaxial cable. Open circuit isolation is thereby significantly improved while maintaining optimum closed circuit conduction characteristics. Although the arrangement described and contemplated in the afore-cited Church et al. patent provides for the serial positioning of the reed contacts along the same longitudinal axis, it is apparent and known that the reed contacts may be arranged in individual axes in a folded, "zig-zag" manner to achieve a more compact switch package as long as the contact spacing restraints defined are adhered to.
In the afore-cited Church et al. switch the reed contacts are serially connected in the inner conductor of a typical coaxial tubular outer conductor. As a result, when the contacts are closed by the energization of windings wound on the outer conductor, the switch construction does not differ substantially in form from the coaxial cable in which it is connected. In a known departure from the typical coaxial inner-solid, outer-tubular conductor switch construction, a single copper sheet is formed to present three adjacent channels within the two outer channels of which individual, electrically isolated reed spring contacts are placed. The reed spring contacts again comprise the inner conductors but here the enclosing copper channels comprise the outer conductors of two electrically distinct coaxial conducting paths. The contacts are operated by a winding about the entire construction and the inner channel conveniently offers an enclosure for a permanent magnet which may be employed to coact with the spring contacts. The "corrugated" copper sheet thus serves to isolate the two conducting paths. A readily fabricated, low cost, and compact switch construction is thus realized.
It is an object of the present invention to achieve high open-circuit isolation in a multiple reed spring coaxial switch construction which, by integrating outer conductor segments into a single unitary element, also achieves significant savings in materials, fabrication time, and manufacturing costs.
It is also an object of this invention to provide a new and novel coaxial switch construction which combines the advantages of multiple contact isolation and a unitary outer conductor element.